Engine starter



June 10, 1941. J DYER 2,245,437

ENGINE STARTER Filed Jan. 9, 1936 3 Sheets-Shet 1 ATTORNEM June 10,1941. .L DYER 2,245,437

ENGINE STARTER Fil ed Jan. 9, 1936 3 Sheets-Sheet 2 JunelQ, 1 941. J. B.'DYEW 2 2 4,431

ENGINE STARTER Filed Jan. 9, 1936 3 Sheets-Sheet 3 INVE TOR M ATTORNE?/m/L/i Patented June 10, 1941 2,245,437 ENGINE STARTER John B. Dyer,Pendleton, Ind., assignor to General Motors Corporation, Detroit, Mich,a cor poration of Delaware Application January 9, 1936, Serial No.58,278'

19 Claims.

This invention relates to improvements in engine starters and moreparticularly in the type of apparatus disclosed in my copendingapplication Serial No. 36,866, filed. August 19, 193-5.

The engine starter of my copending application No. 36,866 comprises apair of driving discs located on Opposite sides of a driven discconnected with the engine to be started. These driving discs are movedby means independent of the starting motor axiallly along a shaft whichsupports them into engagement with the driven disc. The connectionsbetween these driving discs and the shaft are such that when thestarting motor operates to turn the shaft, the driving discs will hepressed against the driven discs with pressure suiiicient to insure agood driving connection for engine starting purposes and, when theengine becomes self-operative, this driving pressure will be relieved sothat the engine cannot drive the starting motor; More specifically theengine starter of my copending application comprises a tubular shaftmounted to slide upon the starting motor shaft and longitudinallysplined thereto. This tubular shaft carries one of the driving discs.The other driving disc is provided by a sleeve mounted to slidelongitudinally upon the tubular shaft. One end of this sleeve isprovided with camming members cooperating with camming rollers mountedupon and driven by the tubular shaft. These cams and rollers are soconstructed and arranged that relative rotary movement between thesleeve and tubular shaft produces relative longitudinal movement. Inorder to cause the driving discs to be moved into engagement with thedriven disc prior to the operation of the starting motor, the starter ofmy copending application provides means under the control of theoperator to cause the tubular shaft to move longitudinally so as to movethe driving disc carried thereby into engagement with the driven disc.After this occurs, the sleeve is caused to rotate by means independentof the motor whereby, due to the coaction between thecams of the sleeveand rollers of the shaft, the sleeve is caused to move longitudinally tomove the other driving disc against the driven disc.

The present invention aims to improve upon the engine starter of mycopending application by simplification of construction which results inreducing the cost of manufacture, while at the same time maintainingeficiencmdurability and quietness of operation. In carrying out this aimof the present invention my improved starter comprises chiefly a tubularshaft longitudinally splined to :the driven shaft and providing one ofthe driving discs, a sleeve providing the other driving disc mountedupon the tubular shaft and connected therewith by camming members whichare provided externally of the tubular shaft and internally of thesleeve. These cammingmembers gral with the shaft 38.

are preferably mating helical ball bearing races which cooperate'toreceive a plurality of ball'bearings which in effect act asscrew-threads relative to the inner tubular shaft and outertubularsleeve. The plurality of ball bearings provide an efiicientanti-friction connection between the sleeve and the shaft while at thesame time providing the necessary strength for an effective cammingconnection between these parts.

Further objects and advantages of the present invention will be apparentfrom the following description, reference being had to' the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

Fig. 1 is a side view partly in section showing a preferred embodimentof the invention in its normal condition. V

Fig. 2 is a Wiring diagram thereof.

Fig. 3 is a fragmentary longitudinal sectional View of a startingapparatus.

Figs. 4, 5, 6 and 7'are sectional views taken respectively on the linest4, 55, 6-6 and 1-1 of Fig. 3.

Figs. 8, 9 and lOare diagrammatic views similar to Fig. 3 but showingthemechanism in different positions of operation.

The motor 21 for starting the internal combustion engine is preferablyan electric motor comprising field frame 2i associated with an end frame22 and a housing 23 which carry bearings 24 and 25, respectively, forthe motor armature shaft 26 which carries an armature ill.

Referring now particularly to Figs. 3 to 7 the shaft 26 carries atubular shaft 3i) which is splined at St to the shaft 2t so that thetubular shaft 39 is at all times drivingly connected with the shaft 26but may slide thereon to a limited extent. The tubular shaft 36 is urgedagainst the end of the bearing 25 by spring 32 which surrounds thearmature shaft 28 and which is located between the armature 2'5 and theleft hand end of the tubular shaft 30.

The shaft 38 carries driving disc 33 and driving disc 34 adapted to moveinto engagement with and to drive a driven disc 35 connected with theengine to be started. Disc 33 is preferably inte- The driving disc 3d isconnected with shaft 36 through a screw thread connection which isprovided by a plurality of balls 38 occupying mating helical grooves 39and 45) provided respectively by'the shaft 38 and the tubularsleeve-like extension 35a of driving disc 34. The screw threadconnection between the driving disc 34 and the shaft 36 is such that,after the discs 33 and Zifihave been moved into engagement with thedriven disc 35 by means to be described, rotation of the motor shaft 39in a clockwise direction as viewed from the right end of Fig. 3 willcause the driving discs to be wedged against the driven disc with apressure suiiicient for engine starting purposes, and so that, after theengine becomes self operative and the driven disc 35 attempts to rotatethe driving discs 33 and 34 faster than they can be rotated by thestarting motor, the driving pressure between the driving discs and thedriven disc will be relieved so that the engine cannot drive thestarting motor at excessive speed.

There are certain important advantages which result from using as thecamming connection between the shaft 3%] and the driving disc sleeve 34aa screw thread provided by ball bearings disposed in a helical raceprovided by mating helical grooves of the shaft 30 and sleeve 34a. Theseball bearings provide an excellent anti-friction support for the disc 34upon the shaft 30 so that relative rotary and longitudinal movementbetween the disc 34 and shaft 39 may take place freely. This isimportant in connection with the operation of the means, to bedescribed, for causing the driving discs to be engaged with the drivendisc prior to operation of the starting motor. The free connectionbetween the shaft 39 and the disc 34 is important also in connectionwith the disengagement of the driving disc with the driven disc when theengine becomes self-operating. Great freedom of movement between thedriving disc 33 and 34 is necessary in order that the driving discs willclear the driven disc very promptly upon the over running of the drivendisc with respect to the driving discs when the engine fires. The use ofa plurality of ball bearings in a helical race is important since thewedging action which takes place between the driving discs while themotor is cranking the engine will be distributed over a relatively largenumber of parts so that the wear and possibility of breakage isminimized. It should also be noted that, by locating the cammingconnection between the driving discs externally of one and internally ofthe other, the length of the tubular extensions from the two drivingdiscs has been made less as compared with the construction shown in mycopending application, wherein the wedging cams are provided at the endof the tubular extension of one of the driving discs.

The engine starter includes a means independent of the starting motorfor causing the driving discs 33 and 34 to be moved into engagement withthe driven disc 35 before the starting motor operates to cause thedriving discs to be wedged against the driven disc with pressuresufficient to transmit torque sufficient for engine starting purposes.This means for causing a-preliminary engagement of the driving discswith the driven disc will now be described.

The disc 3 has its tubular extension 34a provided exteriorly with aplurality of helical splines ti adapted to be engaged by the internallyspllned flange d2 of a sleeve d3 which is supported by a disc 44 rivetedto the left hand end of shaft 35. Disc l has tongues 3? received by alongitudinal groove d8 of sleeve 33. A spring 65 is located between thedisc 4:3 and the flange 42 and tends to maintain the relative locationof the sleeve t3 and disc 3% as shown in Fig. 3, that is, with thetongues ll bearing against the left hand ends of grooves 418. The sleeve33 is longitudinally splined to the tubular shaft Due to the great massof parts connected with the shaft 3i? including the armature shaft 26and the armature 2 the shaft 38 tends to remain stationary as the sleeve13 is moved longitudinally. Hence, the sleeve 33 moves: longitudinallywithout rotating substantially. The pitch of the splines 4| formed onthe sleevelike hub 34a of disc 34 is such that, as the sleeve 43 ismoved toward the left from its position shown in Fig. 3 the disc 34 willrotate relative to the shaft 33 in a direction such as to cause the disc34 to move into engagement with the disc 35.

In order that the sleeve 43 may be moved toward the left from itsposition shown in Fig. 3 it is providedwith an external flange 49 forreceiving the ends 56 of a bifurcated lever if? having at its upper endan elongated notch H which receives a pin '12 carried by bifurcatedbracket 13 integral with an L-shaped bracket 14 attached to anelectromagnet frame mounted upon the motor frame 2i. A spring 16surrounds a stud T! attached to the bracket 13 and urges the upper endof the lever Ill against the pin 12.

The lever Ill is actuated electromagnetically by means which will now bedescribed with reference to Fig. 2. As shown diagrammatically in Fig. 2,magnet frame l5 encloses electromagnet windings 8D and BI surrounding amovable solenoid armature 82 guided by the magnet frame 15 for slidingmovement toward a stationary core 83 which is located in the magneticcircuit of the electromagnet. The armature 82 is connected by a link 8dwith the lever lll. Armature 82 is associated with a rod 35 upon whichis mounted a non-conducting collar 88 yieldingly urged by spring 87against a shoulder 88, the spring 81 being confined between the collar86 and a washer as held from moving toward the right by a pin 93. Aspring 3| located between a stationary part 92 and the rod normallymaintains the rod 35 and the armature 32 in the normal position as shownin Fig. 2.

The collar 83 carries a movable switch contact 95 adapted to engage withcontacts 53 and 3 of the starting motor switch. Contact 96 is connectedby wire 93 with a switch terminal 99. Contact 91 is connected with thestarting motor 23 which is grounded at I63. Terminal 99 is connectedwith storage battery NH grounded at 32. Terminal 93 may be connectedsimultaneously with terminals I63 and 194 by a movable contact I95.Terminal IE4 is connected with contact tad of an antomatic switch havingalso a terminal 10! connected with windings 8G and 8|, 8i beingconnected with contact 91 and 39 being grounded at lfiB. This automaticswitch designated in its entirety by numeral H9, comprises a suctionchamber ill connected by pipe H2 with the intake manifold of an internalcombustion engine. One wall of the chamber H! is provided by a diaphragmH3 which is attached to switch contact H4, said contact being normallyin engagement with contacts I86 and lfil, said engagement being effectedthrough the action of a spring H5 located so as to press the diaphragmH3 downwardly as viewed in Fig. 2.

As stated before, this starter drive includes the feature of causing thedriving discs 33 and 36 to be moved into engagement with the driven disc35 before operating the starting motor 28. This is accomplished by meansindependent of the motor, namely, the electromagnet means showndiagrammatically in Fig. 2. The manner in which the driving discs arecaused to engage the driven discs will now be described particularlywith respect to Figs. 8, 9 and 10.

To start the engine the operator turns the switch contact I05 so as tocause it to engage the contact I03 and the contact I04. The ignition isthen turned on, the ignition circuit being connected with the terminal103 which is then connected'with the battery NH. The terminal H34 beingthen also connected with battery ill I, current will flow from thebattery Illl through the windings 8E3 ande i, the former being directlygrounded at H18 and the latter being indirectly grounded through themotor 2E). The electromagnet windings 80 and BI being energized, thearmature 82 will move toward the left thereby causing the lever 10 tomove to swing toward the left in a clock-wise direction around its pivot72. During the movement of the lever 10 the contact 95'will bemovingtoward contacts 96 and 91; but before engagement of these contactsactually occurs, the driving discs 33 and 34 will be'brought intoengagement with the driven disc 35 in a manner which will be apparentfrom a consideration of Figs. 8, 9 and 10.

As lever 10 moves toward theleft the entire drive assembly will be movedbodily toward the left from the position shown in Fig. 8 to that shownin Fig. 9 thereby causing the driving disc 33 to engage the driven disc35. This movement of the drive assembly is resisted by the spring 32which normally holds the shaft 39 against the bearing 25.

Further movement of the lever l toward the left causes the sleeve 43 tomove to the left relative to the driving disc sleeve 3% thereby causingthe driving disc 34 to be rotated in such direction relative to theshaft 30 that the disc 34 will be moved from its position shown in Fig.9 to that shown in Fig. 10 wherein said disc 34 engages the.

driving disc 35. The driving discs have now completed their preliminarymovements into engagement with the driven discs. Hence the starter drivehas been rare-conditioned for operation by the electric motor. After thedriving discs have completed their preliminary movement the lower end ofthe lever 10 cannot move any further toward the left.

Continued motion of thesolenoid armature 82 toward the left to closecontacts 95, 96 and 9'! may take place by reason of the fact that thereis lost motion between the upper end of the lever 10 and the pivotbearing 12. Just before these contacts are closed, the spring it is heldby the solenoid armature 82 under compression, so that yielding pressureis applied between end 50 of lever l0 and the sleeve flange 44.Therefore; it is only after the driving discs have been brought intoengagement with the driven discs under yielding pressure that the motorswitch contact 95 is caused to engage the stationary contacts 96 and 91.When this occurs the motor operates to turn the shaft 26. The winding 8|is then short circuited and winding 30 only is effective to hold themotor switch closed. Winding 8:] comprises preferably a large number ofturns of fine wire and winding 8! fewer turns of coarser wire. Bothwindings are required to effect movement of the armature 82 initiallytoward the core 63 but winding 80 only is required to maintain thearmature 82. in its attracted position. The starting motor then willoperate to cause the shaft 26 to rotate in a clock-wise direction asviewed looking in the direction of arrow 60 of Fig. 8. At the instantthe motor starts to turn the shaft 26, the driving discs 33 and 34 beingthen in engagement with the driven disc 35, the first action istoincrease the pressure between the driving discs and the driven discs dueto the cooperation of the screw thread connection between the drivingdiscs.

Thus in responseto the operation of the electrio motor in turning theshaft 26 the driving discs '33 and-'34 are caused to press against thedriven disc 35 with pressure sufficient to insure a driving engagementbetween the electric motor and the engine for engine starting purposes.Hence the electric motoris drivingly connected with theengine and willstart the latter. This driving engagement has been effected noiselesslydue to the fact that means independent 'ofthe. motor have been employedfor moving the'driving discs against'the'driven disc before the motor isconnected with the current source. Then when the motoriscauseol tooperate it produces noiselessly-a pressure between the driving anddriven discs suflicien't for enginestarting purposes.

When the engine becomes self operative and attainsa speed such that thelinear speed of the driven disc 35 as effected by the engine exceeds thelinear speed ofthe driving discs 33 and 34 as effected by the'startingmotor, driving engagement between the driving and driven discs of thestarter drive is automatically released. This is accomplished that dueto the fact that as the driven disc35 tends to run ahead of the drivingdiscs 33 and '34, the disc 34 tends to screw itself away fromthedisci3fi, and thus permit separation of the driving discs from thedriven disc. After the engine starts the electromagnet is automaticallydeenergized bythe opening of the automatic switch H0. The suctionproducedin the engine intake when operating will be sufficient to raisethe diaphragm H3 against the action of the spring H5, thereby separatingcontact H4 from contacts H36 .and I111. The spring 9| will then bereleased to effect movement of the parts 85, 82, 84 and i0 toward theright as viewed in Fig. 2. The spring 16 willalso be released so as tomove the upper end of the lever 10 toward the right returning it to itsnormal position. In this way the engine starter drive parts are restoredto normal position as shown in Figs. 1, 2, 3, and 8.

Since the ends 59 of lever Hi bear yieldingly upon the sleeve flange 49and the internal flange 42 of sleeve 43 will bear yieldingly against thehelical splines 4! of the tubular sleeve 3% of driving disc 34.Therefore, since the sleeve 43 .is yieldingly urged toward the left thedriving disc 33 will be yieldingly. urged against the driven disc 35;and, since the driving disc 34 is caused to rotate by the sleeve 43under the action of yielding pressure, the driving disc 34 will beyieldingly pressed against the driven disc 35. Therefore both drivingdiscs are urged by means independent of the motor against the drivendisc with yielding pressure. This is desirable for the purpose ofcompensating for wear of the friction Surfaces of the driving and drivendiscs. There is another purpose which is important. If the engineshouldmake a weak or false start and fail to attain a speed sufiicient toinsure self operation, the spring 76, being then. held under pressuregreater than normal by the electromagnet, an actuating force is. therebystored in the spring it which tends to maintain the preliminary contactbetween the driving discs and the driven discso that, if thereis anytendency to relievepressure between the driving and driven discs duringa false or weak start of the engine, this tendency will be counteractedby the tendency of the spring 16 to urge the driving discs almostinstantaneously back into cooperative relation with the .drivendiscs. Inother words, the spring 13 forms a function analogous to that performedin the conventional one way or overrunning clutch by .thesprings which:are provided-reach for urging a clutch roller into wedging engagementbetween the clutch cam and the clutch shell. Thus when the engineattempts to start on its own power and tends to release the drivingengagement between the driving and driven discs and then fails to attaina speed sufficient to maintain self operation, the starting motor driveis at all times ready to pick up the load of cranking the engineinstantaneously.

The electromagnetic means which. operates independent of the motor tocause the driving discs to be pressed against the driven discs beforethe motor is operated is not only a convenient means for preconditioningthe starter drive but is one which is well adapted to cooperate with thestarter drive of this type. It requires a relatively small force to movethe driving disc 33 from its position shown in Fig. 8 to that shown inFig. 9 where it engages the driven disc 35 and it requires asubstantially greater force to move the driving disc 34 into engagementwith the driven disc 35 and to effect compression of spring 16 beyondits normal state of compression. The electromagnetic device is welladapted to provide the actuating forces which are required. At first theattraction upon the solenoid armature 82 is relatively small but theforce required to move the driving disc 33 toward the left is relativelysmall. As the solenoid armature 82 approaches the core 83 the attractionincreases. greatly to give the necessarily greater force required tomove the driving disc 34 against the driven disc 35 and to compress thespring 16 beyond its initial state. It is also necessary that thestarter switch contact 95 be pressed against the stationary contacts 98and 91 with a pressure sufficient to insure a good electrical contact.The electromagnet is also well adapted to give this final pressure whichis needed between the starter contacts in the starter switch. Duringfinal movement of the solenoid armature 82 toward the left when the airgap between the armature and core is closing up the pull upon thearmature increases tremendously and is. sufficient not only to effectthe desired movements of the engine starter drive but also to compressthe spring 81 beyond its initial state of compression and to forcemovable contact 95 firmly against the stationary contacts 96 and 91.

The electromagnet is so constructed as to efiect a pull on the armature82 sufficient to make good electrical contact between the contacts inthe starter switch. The magnetic pull required for closing the switchproperly is greater than that sufficient for preconditioning the enginestarter drive prior to actual operation of the motor.

As undue pressure between the driving discs and the driven disc prior tooperation of the motor is as undesirable as insufficient pressure thespring 16 operates while the motor switch is closed to limit the forcewhich can be applied by the electromagnet to the shifting lever 10. Thespring 16 is so designed that upon being deflected a certain distance bythe armature 82 when closing the motor switch the spring will exert theproper force upon the lever 10 tending to rotate it clockwise about itspivotal connection with the link 84. In this way the spring 16 operatesnot only as a spring exerting yielding pressure upon the shifting collarflange 49 for the purposes herein specified but spring 16 operates alsoas a means for limiting the amount of pressure which can be effected bythe electromagnet.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form,

it is to be understood that other forms might be adopted, all comingwithin the scope of the claims which follow.

What is claimed is as follows:

1. For use in an engine starting apparatus having a starting motoradapted to operate the engine to be started, a starter drive throughwhich said motor operates the engine and having, in combination, a pairof driving discs adapted for engagement with opposite faces of a drivendisc connected with the engine, a rotatable element operable by thestarting motor and providing one of the driving discs, a tubular memberabout said element and providing the other driving disc, and means foreffecting relative axial movement between said driving discs in responseto rotary movement of one relative to the other, said means includingcamming provisions formed upon a cylindrical surface of said element andupon the cooperating cylindrical surface of said tubular member, andsaid starter drive having means adapted to be acted upon by a forceother than that of the starting motor to effect an initial movement ofsaid driving discs for engagement with said driven disc.

2. For use in an engine starting apparatus having a starting motoradapted to operate the engine to be started, a starter drive throughwhich the motor operates the engine and having, in combination, a pairof driving discs adapted \for engagement with opposite faces of a drivenmember, and said starter drive having means 4 adapted to be acted uponby a force other than that of the starting motor to effect an initialmovement of said driving discs for engagement with said driven disc.

3. For use in an engine starting apparatus having a starting motoradapted to operate the engine to be started, a starter drive throughwhich the motor operates the engine and having, in combination, a pairof driving discs adapted for engagement with opposite faces of a drivendisc connected with the engine, a rotatable element operable by thestarting motor and providing one of the driving discs, a tubular memberabout said element and providing the other driving disc, and means foreffecting relative axial movement between said driving discs in responseto rotary movement of one relative to the other, said means including arow of bearing balls received by mating helical races formed in thecooperating surfaces of said rotatable element and said tubular member,and said starter drive having means adapted to be acted upon by a forceother than that of the starting motor to effect an initial movement ofsaid driving discs for engagement with said driven disc.

4. For use in an engine starting apparatus 'having a starting motoradapted to operate the engine to be started, a starter drive throughwhich the motor operates the engine and having, in combination, a pairof driving discs adapted for engagement with opposite faces of a drivendisc connected with the engine, a tubular shaft providing one of thedriving discs and adapted to be mounted upon the armature shaft of thestarting motor and to be driven thereby, a tubular member about thetubular shaft and providing the other driving disc, and means foreffecting relative axial movement between said driving discs in response.to rotary move- .which themotor operates the engine and having, incombination, a pair of driving discs adapted for engagement withopposite faces of a driven disc connected with the engine, a tubularshaft providing one of the driving'discs and .adapted to be mounted uponthe armature shaft ofthe starting motor and to be driven thereby, atubular member about the tubular shaft and providing the other drivingdisc, and meansfor effecting relative axial movement between saiddriving discs in response to rotary movement of one relative to theother, said means including coacting screw thread provisions formedexternally of the tubular shaftand internally of said tubular member,and said starter drive having means adapted .to be acted upon by a forceother than that of the-starting motor to effect an initial movement ofsaid driving discs for engagement with said driven disc.

6. ,For use in an engine starting apparatus having a starting motoradapted to operate the engine to be started, a starter drive through iwhich the motoroperates the engine and having, in combination, a pair ofdriving discs adapted for engagement with opposite faces of a drivendisc connected with the engine, a tubular shaft providing one of thedriving discs and adapted to be mounted upon thearmature shaft of thestarting motor and to bedriven thereby,.a tubular member about thetubular shaft and providing the other driving disc, and means foreffecting relative axial movement between said driving discs in responseto rotary movement of one relative tothe other, said means including arow of bearing balls received in mating helical races formed on thecooperating surfaces of said tubular shaft and tubular member, and, saidstarterdrive having means adapted to be acted upon by a force other thanthat of the starting motor to eifectianinitial movement of said drivingdiscs for engagement with said driven disc.

7. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a starting-motoroperated shaft providingone of the driving discs, a tubular member surrounding the shaft andproviding the other driving disc, means for effecting relative axialmovement between said driving discs in response to rotary movement ofone relative to the other, said means including camming provisionsformed upon the cylindrical surface of the shaft and upon the insidecylindrical surface of said tubular member and a shifter sleeve having alongitudinal-spline connection with the shaft and a helical-splineconnection with the tubular member and adapted to cooperate with adevice for moving the sleeve longitudinally.

8. In an engine starter, the combination of a pair of driving discsadapted forengagement with opposite faces of a driven disc connectedwith the engine to be started, a starting-motor-operated shaft providingone of the driving discs, .a tubular member surrounding the shaft andproviding the other driving disc, means for effecting .relative axialmovement between said driving discs in response to rotary movement ofonerelative to the other, said means including coasting screw threadprovisions formed externally of the shaft and internally of the tubularmember and a shifter sleeve having a longitudinal-spline-connection withthe shaft and a helical-spline-connection with the tubular member andadapted to cooperate with a device for moving the sleeve longitudinally.

9. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a starting-motor-operated shaft providingone of the driving discs, a tubular member surrounding the shaft andproviding the other driving disc, means for. effecting relative axialmovement between said driving discs in response to rotary movement ofone relative to the other, said means including a row of bearing ballsreceived by mating helical races provided by the shaft andtubular-member and a shifter sleeve having alongitudinal-spline-connection with the shaft and ahelical-spline-connection with the tubular member and adapted tocooperate with a device for moving the. sleeve longitudinally.

10. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven discconnectedwith the engine to be started, a tubular shaft providing one ofthe driving discs and adapted to be mounted upon the armature shaft of astarting motor-and tobe driven thereby, a tubular member surrounding theshaft and providing the other driving disc, means for effecting relativeaxial movement between said driving discs in response to rotary movementof one relative to the other, said means including camming Iprovisionsformed uponthe outside cylindrical surface of, the shaft and upon theinside cylindrical surface of the tubular member and a shifter sleevehaving a longitudinal spline connection with the shaft and ahelical-spline-connection .with the tubular member and adapted tocooperate with a device for moving the sleeve longitudinally.

11. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disoconnectedwith the engineto be started, a tubular shaft providing one of thedriving discs and adapted to be mounted upon the armature shaft of astarting motor and to be driven thereby, a tubular mempair of drivingdiscs adapted for engagement with opposite faces of a driven discconnected with the engine to be started, a tubular shaft providing oneof the driving discs and adapted to be mounted upon the armature shaftof a starting motor and to be driven thereby, a tubular membersurrounding the shaft and providing the other driving disc, means foreffecting relative axial movement between said driving discs in responseto rotary movement of one relative to the other, said means includnig arow of bearing balls received by mating helical races provided by theshaft and tubular member and a shifter sleeve having alongitudinal-spline-connection with the shaft and ahelical-spline-oonnection with the tubular member and adapted tocooperate with a device for moving the sleeve longitudinally.

13. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a starting-motor-operated shaft providingone of the driving discs, a tubular member surrounding the shaft andproviding the other driving disc, means for effecting relative axialmovement between said driving discs in response to rotary movement ofone relative to the other, said means including camming provisionsformed upon the cylindrical surface of the shaft and upon the insidecylindrical surface of said tubular member, and means independent of thestarting motor for causing the driving discs to engage the driven discbefore the motor operates.

14. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a starting-motor-operated shaft providingone of the driving discs, a tubular member surrounding the shaft andproviding the other driving disc, means for effecting relative axialmovement between said driving discs in response to rotary movement ofone relative to the other, said means including coacting screw threadprovisions formed externally of the shaft and internally of the tubularmember, and means independent of the starting motor for causing thedriving discs. to engage the driven disc before the motor operates.

15. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a starting-motoroperated shaft providingone of the driving discs, a tubular member surrounding the shaft andproviding the other driving disc, means for effecting relative axialmovement between said driving discs in response to rotary movement ofone relative to the other, said means including a row of bearing ballsreceived by mating helical races provided by the shaft and tubularmember, and means independent of the starting motor for causing thedriving discs to engage the driven disc before the motor operates.

16. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a tubular shaft providing one of thedriving discs and adapted to be mounted upon the armature shaft of astarting motor and to be driven thereby, a tubular member surroundingthe shaft and providing the other driving disc, means for effectingrelative axial movement between said driving discs in response to rotarymovement of one relative to the other, said means including cammingprovisions formed upon the outside cylindrical surface of the shaft andupon the inside cylindrical surface of the tubular member, and meansindependent of the starting motor for moving the tubular shaftlongitudinally to cause its driving disc to engage the driven disc andfor rotating the tubular member to cause the driving disc of saidtubular member to engage the driven disc before the motor operates.

17. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a tubular shaft providing one of thedriving discs and adapted to be mounted upon the armature shaft of astarting motor and to be driven thereby, a tubular member surroundingthe shaft and providing the other driving disc, means for effectingrelative axial movement between said driving discs in response to rotarymqvlement of one relative to the other, said means including coactingscrew thread provisions formed externally of the shaft and internally ofthe tubular member, and means independent of the starting motor formoving the tubular shaft longitudinally to cause its driving disc toengage the driven disc and for rotating the tubular member to cause thedriving disc of said tubular member to engage the driven disc before themotor operates.

18. In an engine starter, the combination of a pair of driving discsadapted for engagement with opposite faces of a driven disc connectedwith the engine to be started, a tubular shaft providing one of thedriving discs and adapted to be mounted upon the armature shaft of astarting motor and to be driven thereby, a tubular member surroundingthe shaft and providing the other driving disc, means for effectingrelative axial movement between said driving discs in response to rotarymovement of one relative to the other, said means including a row ofbearing balls received by mating helical races provided by the shaft andtubular member, and means independent of the starting motor for movingthe tubular shaft longitudinally to cause its driving disc to engage thedriven disc and for rotating the tubular member to cause the drivingdisc of said tubular member to engage the driven disc before the motoroperates.

19. In an engine starter, the combination of a tubular shaft adapted tobe mounted upon the armature shaft of an engine-starting-motor andhaving a longitudinal-spline connection therewith, a tubular membersurrounding the tubular shaft and having a screw-thread connectiontherewith provided by a row of bearing balls received by mating helicalrecesses provided by said tubular parts, a pair of driving discs adaptedto engage a driving disc connected with the) engine to be started, saiddriving discs being provided, respectively, by said tubular parts, ashifter sleeve surrounding the tubular member and having at one end aninternal annular flange which has a helical spline connection with theoutside cylindrical surface of the tubular member and having at theother end an external annular flange for engagement with a shiftingdevice, a member attached to the tubular shaft and having partsprojecting into longitudinally extending slots provided in the shiftingsleeve, and a. helical coil spring located between said member attachedto the tubular shaft and the internal annular flange of the shiftersleeve.

JOHN B. DYER.

